THE PLASMA CONCENTRATION OF UNCONJUGATED OESTRONE AND 17β-OESTRADIOL DURING THE NORMAL MENSTRUAL CYCLE

Abstract
By a double isotope derivative technique, the content of "free" estrone and 17[beta]-estradiol was determined in plasma from normally menstruating women. Through the cycle the concentration of the 2 hormones was found to range from 0.1-0.3 [mu]g/1, substantially higher values being found only in the middle third of the cycle. Daily determinations around the time of ovulation in a few women showed a short-lasting increase up to 1 [mu].g/l. This increase appears to precede ovulation, and the authors advance the idea that this increase is a contributory cause of ovulation.